In manufacturing of a semiconductor device, various processes such as a film forming process, a heating process and an etching process are performed on an object to be processed (e.g., a semiconductor wafer) within a processing vessel. A product, such as an unreacted reaction product or a reaction by-product, according to a variety of processes, is contained in an exhaust gas discharged from the processing vessel in such a process. When the product is deposited on an inner wall of an exhaust pipe or a vacuum pump, in some cases, a decrease in exhaust performance or a trouble of the vacuum pump may occur. Therefore, conventionally, an exhaust trap for trapping the product has been known.
However, the conventional exhaust trap had a short PM (Preventive Maintenance) cycle indicative of a period during which preventive maintenance is performed.